It's worth noting that the airfoil on this wing is prone to funky stall behavior. The original design uses a more symmetrical airfoil. But the flat bottom airfoil prints really well, so maybe it's worth it?

I think if you increased the chord (made the wing thicker) than that would help a lot with the stalling problem.Â It should give more lift at slower speeds, without inducing too much extra drag.Â You could probably go as far as to Double the chord, but probably 150% would be sufficient.